Shuttle drive mechanisms



Aug. 7, 1962 c. F. FITZGERALD ETAL 3,048,134

SHUTTLE DRIVE MECHANIsMs Original Filed Feb. 8, 1957 2 Sheets-Sheet 1 d www@ o @1mm ZuO fmMf mFJM.: u@ mi nmmmfy CAB Aug. 7, 1962 C. F. FITZGERALD ETAL SHUTTLE DRIVE MECHANISMS Original Filed Feb. 8, 1957 2 Sheets-Sheet 2 3,tl4i8,13/i SHUTTLE D MECHANISMS Charles Ii. Fitzgerald, Beverly, and Arthur Jl. Murphy, Saugus, Mass., assignors to United Shoe Machinery Corporation, Boston, Mass., a corporation of New Hersey Original application Feb. 8, 1957, Ser. No. 638,986, now Patent No. 2,979,691, dated Apr. 11, 1961. Divided and this appiieation Dec. 23, 1959, Ser. No. 861,669

3 Claims. (Cl. liz- 38) rIhis invention relates generally to improvements in lockstitch shoe sewing machines of the McKay type having rotatably mounted shoe entering horns, such as the machines disclosed in United States Letters Patent No. 1,885,927 granted November l, 1932, upon application of B. T. Leveque and No. 1,914,936 granted lune 20, 1933, upon application of P. Ashworth. More particularly the present invention is directed to improved shuttle driving means particularly useful in connection with a rotary shuttle in such machines.

The present invention has already been disclosed in application for United States Letters Patent Serial No. 638,986 filed February 8, 1957, and now United States Letters Patent No. 2,979,061, `granted April 11, 1961, of which the present application is a division. The parent application, in addition to the present subject matter, also discloses a novel thread severing means, now application Serial No. 856,955, filed December 3, 1959, and novel driving and stopping devices for the needle and stitch-forming devices to permit the shuttle to remain in motion after the needle is stopped at the end of a seam so that the last stitch is completely formed and set in the work.

Each of the machines of the above-identified patents is constructed with a single beak oscillating shuttle which receives a loop of needle thread at each oscillation and passes the needle loop about the thread case to form a lockstitch seam. The extent of shuttle motion is limited so that the point of shuttle beak never crosses the locking thread and there is accordingly no possibility that the locking thread might be displaced by the shuttle at a critical time during the formation of the stitch.

In the present machine, in order to attain greater sewing speeds than are possible with oscillating shuttles, the shuttle is revolved continuously at the rate of two complete revolutions for each reciprocation of the needle. As a result, the time required for each needle loop to be passed about the locking thread case is approximately one-third of the duration of the sewing cycle. The shuttle rotates about an axis inclined to the horizontal so that its beak when downwardly oriented is closest to the path of the needle for receiving the loops of needle thread with minimum motion of the loop presenting instru- `mentalities of the machine. The effect of the inclined axis of the shuttle is to bring into contact with the locking thread irregularly formed shuttle surfaces, thereby tending to displace the thread and to disturb the uniformity of the seam.

It is, accordingly, a general object of the present invention to improve the uniformity of seams inserted by McKay type shoe sewing machines having shuttles which revolve about axes inclined to the horizontal.

lt is another object to deect the locking thread in such machines away from irregularly formed shuttle surfaces.

It is yet another object to guard such rotary shuttles against vibration or speed variations which impair their proper functioning.

It is still another object to achieve reliability of operation in the type of machine already described without appreciably increasing the cost of manufacture or the complexity of the machine.

lidhlit Patented Ang. 7, 13,62

In the achievement of the foregoing objects a feature of the invention resides in a novel form of shuttle driver which passes through. the throat and extends beyond the front face of the shuttle to engage the locking thread extending downwardly from the locking thread case to the work. The end of the shuttle driver is formed with a gently sloping surface starting behind the front face of the shuttle and emerging forwardly of the front face at a point to engage the locking thread and deliect it out of the path of the shuttle beak.

According to another feature of the invention the shuttle driver is rotated through connections including an overload relief clutch and a universal joint which couple the shuttle driverk to a main vertical drive shaft in the machine. The presence of the universal joint reduces the need for accuracy of axial alinement between the shuttle driver itself and the other part of the shuttle drive and the overload relief clutch serves the conventional purpose of preventing damage to the shuttle and its driving connection in the event that the shuttle should accidentally engage an obstruction. By inter-posing a single spring, the pressure of which may be accurately regulated, between the clutch and the universal joint it is possible to maintain the clutch members in driving engagement and also to apply an axial load to the members of the universal joint thereby preventing vibration and other speed variations detrimental to the uniformity of the seam.

The foregoing objects are achieved in accordance with the features of the invention which will be more fully appreciated from the following detailed description of an illustrative embodiment taken in connection with the accompanying drawings in which,

FIG. l is a view in left side elevation of a McKay type shoe sewing machine including shuttle driving means in accordance with the present invention;

FIG. 2 is a detail view on an enlarged scale and partly in cross section illustrating details of the shuttle drive;

FIG. 3 is a fragmentary View in front elevation of a portion of the machine shown in FIG. 1 and illustrating the shuttle and its driver;

FIG. 4 is a detail View in right side elevation of the v shuttle and driver showing the engagement of a locking thread by the extension of the driver beyond the front face of the shuttle.

The machine illustrated in FIG. 1 is similar in some respects to those of the Leveque and Ashworth patents above identified and includes in its general arrangement a shoe entering horn 2, and a sewing head assembly indicated generally at 4, in which are incorporated iustrumentalities for forming stitches, for feeding the work, and for holding the work against the upper surface of the horn.y The stitch-forming instrumeutalities include a straight hook needle 6, which after penetrating the work is threaded by a needle-threading whirl of conventional design, not shown, in the tip of the horn, and withdraws from the work carrying a loop of needle thread. The lockstitch seam is formed by presenting the needle loops to a shuttle 8, which carries eachneedle loop about a locking thread case 10, thereby forming a thread lock with the top or ylocking thread 12. In the present machine the work is fed by a feed point 14 and intermittently clamped against the upper surface of the horn by a presser foot 16, lboth the feeding and clamping of the work being accomplished ina conventional manner.

The machine is driven by an electric motor 18 supported at the rear of the base of the machine. The motor shaft is coupled to a vertical drive shaft 2t) through connections including a treadle controlled clutch 22. For actuating a needle threading whirl located in the tip of the horn and `a take-up mounted below the horn and more fully described in the parent application, the present maaosaisa chine includes a horizontal shaft 24 connected to the vertical drive shaft 20, through a pair of bevel gears 26 and Z8. The upper end of the vertical drive shaft 2.0 is connected by bevel gears to a main composite sewing shaft 30, which carries cams and a crank for driving the needle and for actuating the other necessary work feeding and clamping devices of the sewing head as more fully described in the parent application.

The present shuttle is of `discoidal shape and similar to that employed in the prior machines having a closed rearward end and a forward end which is open to receive the locking thread case 10, best shown in FIG. 3.

` The front end of the locking thread case faces the needle toward which the locking thread is led as it is drawn into the work by a loop of needle thread interlocked with the locking thread by the action of the rotary shuttie 8. As in the machines of the prior patents the present shuttle 8 is formed with a loop entering beak 36 which moves in a circular path defining a plane inclined to the needle so that the beak while in the lower portion of its path is closer to the needle than while it is in the upper portion of its path. Within its beak the shuttle `is formed with a throat recess 33 into which a driver il y lits loosely to impart the rotary motion to the shuttle while at the `same time permitting the loops of needle thread to pass between the shuttle within its throat and the driver. The shuttle and locking thread case are to the extent already described the same as in the prior machines, except that the present shuttle and thread case are of greater axial depth than the prior ones so that a substantially greater supply of locking thread is contained in the thread case.

Another important difference between the present machine and the prior one is in the shuttle driving means including the shuttle driver 40. In the prior machines the shuttle is actuated with an oscillating movement in each sewing cycle, first in one direction to enter and carry each needle loop about the thread case and then in the opposite direction to return to its starting position. At the end of its return movement the shuttle beak of the patented machines occupies approximately the position relative to the locking thread as that shown in FIG. 3. It will be noted that in its starting position the tip of the beak lies to the left of the needle path ready to enter `a needle loop but has not crossed the locking thread. There is accordingly no `danger of the shuttle beak irnpalin y the locking thread and since the shuttle of the patented machines is actuated through an oscillatory gear sector connected to the main sewing shaft in the sewing head the driving connections for the shuttle are more compact and in some respects both simpler and easier to construct. However, the oscillatory shuttle movement has the disadvantage of unduly limiting permissifble sewing speeds by introducing excessive vibration and lost motion which affect the quality of the seam and increase machine wear as speed is increased.

For driving the shuttle in place of the oscillatory actuating devices of the prior machines, the present one includes a continuously rotating drive comprisingbevel gears 42 and 44 mounted respectively upon the vertical shaft 20 and upon an inclined shaft do. The gear 44- has an elongated hollow hub journaled in a split bearing 4.8 on the machine frame and a radially grooved enlargement t) engaging a complementary ribbed collar 52 free to slide on the inclined shaft 46 which is otherwise loose in the hub of the gear 44. The forward end of the shaft 46 is secured to a universal joint, indicated at 54, in turn connected to an alined shaft 56 with the forward end of which the shuttle driver ttl is integrally formed. The ribbed collar 52 and the grooves of the enlargement 50 form a slip connection between the inclined shaft 46 and the gear 44 and the universal joint 54 reduces the necessity for precise alinement between the shaft 56 and the axis of the gear 44, thereby substantially reducing the cost of manufacture of the machine frame. Because of the manner in which the universal joint 54- is applied in the machine, it also assists in substantially reducing vibration in the shuttle driving connections and contributes to a smooth running machine.

In order to avoid lost motion in the shuttle driving connections, the parts of the universal joint 54 are operated under an axial load provided by a compression spring 53 surrounding the inclined shaft 46 and also effective for pressing the ribbed collar 52 into engagement with the grooved enlargement 5d. The spring 53 is compressed between the collar 52 and a pair of check nuts 6@ for adjusting the load of the spring for the dual purpose of preventing displacement of the ribbed collar out of engagement with the grooved enlargement 5t) and, by maintaining the universal joint 54 under a constant axial load, of preventing Vibration 4and other speed variations which are detrimental to the uniformity of the seam. The slip connection 50, 52 normally transmits rotary motion to the shuttle 8 but slips out of engagement when the shuttle is jammed by thread or other extraneous substances.

`So that the action of the locking thread in the present machine will be more fully understood, the timing of the various work feeding and stitch forming instrumentalities of the machine will be briey described, starting with the descent of the needle 6 toward the work. The needle penetrates the work and while in its lowermost position is threaded by the whirl in a conventional manner. As the needle reaches the lowermost point of its travel the shuttle beak 36 is in essentially the same position relative to the path of the needle as is shown in FIG. 3, having approximately completed a revolution during the descent of the needle. The threaded needle retracts from the work and after the needle has cleared the upper surface of the work, the presser foot 16 is raised to release the Work which is advanced a stitch length to the left (FfG. 3) by the feed point 14. During the ascent of the needle the shuttle completes a revolution and as the needle appreaches the uppermost limit of its travel shown in FIG. 3, the point of the shuttle beak is to the immediate left of the path of the needle ready to enter the loop presented by a loop spreader 59 which presses one side of the loop rearwardly to present it to the beak. Thereafter while the needle again descends toward the work the shuttle passes the needle loop about the locking thread case lil and a takeup, described in greater detail in the parent application, assists in setting the stitch which has just been formed.

To deflect the locking thread leading from the thread case ll@ away from the shuttle beak 36 so that the latter will not impale and strand the thread, the shuttle driver 4@ of the illustrated machine projects through the throat recess 38 of the shuttle beyond its forward side facing the needle. The projecting corners' and the edges of the driver are smoothly rounded to prevent abrasion of the thread and the end of the driver is additionally formed with an inclined surface 6i), which intersects the plane of the forward face of the shuttle, so that the locking thread 12 is engaged gently, and deflected gradually out of the path of the shuttle beak before the beak crosses the locking thread to reach the position of FIG. 3. As in the shuttles of the patented machines, the locking thread emerges from the thread case through an opening 62 eccentric with the axis of the shuttle. Advantage is taken of this eccentricity to withdraw the necessary locking thread from the thread case while the opening 62 is moving away from the tip of the horn to its most distant position shown in FIG. 3. It will be noted from FIG. 3 that the locking thread 12 is then in engagement with the thread deecting end portion of the driver 40, thereby contributing with the eccentricity of the opening 62 in the measurement of locking thread for the formation of stitches. Since the gears 42 and 44, and those by which the sewing shaft 30 is connected to the Vertical shaft 20, are calculated for ya speed ratio `of two full rotations of the `shuttle to each reciprocation of the needle 6, the shuttle 8 passes alternately through active rotations in which it carries loops of needle thread and idle rotations during which no needle loops are received. During each active rotation of the shuttle the length of locking thread extending between the opening 62 and the work piece includes a quantity already measured for the formation of the next stitch, and because the locking thread has not yet been engaged by the needle thread when the locking thread is contacted by the end of the driver 40, the locking thread is then loose. Another factor contributing to the looseness of the locking thread lat this time is the fact that the Work has just been fed, thereby shortening the distance between the opening 62 and the point of entry of the locking thread into the work. During the idle rotation of the shuttle, however, the quantity of locking thread taken up in the setting of the prior stitch brings the locking thread into engagement with the driver 40 under tight thread conditions. The end of the driver 01 accordingly engages ythe locking thread under varying conditions of tightness md locseness and the configuration of the driver end, its orientation relative to the eccentricity of the opening 62 and the extent of the projection of the driver end beyond the front face of the shuttle must therefore be carefully selected and balanced to avoid interfering with the uniformity of the seam.

The nature and scope of the invention having been indicated and an illustrative embodiment of the invention having been described in detail, what is claimed is:

1. A lockstitch shoe sewing machine having a rotatably mounted shoe entering horn, stitch-forming and setting devices including a straight hook needle, a discoidal shuttle rotating a plurality of revolutions for each reciprocation of the needle with the rotary path of its beak dening a plane inclined to the needle to bring the beak While in the lower portion of its path closer to the needle than while in the upper portion of its path, said shuttle being yformed with a throat recess within its beak, and a locking thread case about which the shuttle carries each loop of needle thread and from the side of which facing the needle the locking thread is led, in combination with a driver projecting through the throat recess beyond the shuttle plane at the side facing the needle to deflect the locking thread leading from the thread case away `from the shuttle beak.

2. A lockstitch shoe sewing machine comprising a rotatably mounted shoe entering horn, stitch-forming and setting devices including a straight hook needle mounted for reciprocation toward and away from the horn, a discoidal shuttle having a single beak and mounted for rotation about an axis inclined to the path ofthe needle whereby the beak while in the lower portion of its path is closer to the needle than While in the upper portion of its path, the shuttle being formed with a throat recess within its beak, a case holding a supply of locking thread a length of which extends from the case to a work piece supported upon the horn, and means for deecting the locking thread away from the path of the shuttle beak before the beak crosses the Ilocking thread.

3. The sewing machine defined by clairn 2 wherein the detlecting means `comprises a shuttle driver projecting `forwardly through the throat recess partially beyond the front face of the shuttle and having an inclined end surface adapted to engage the thread and to deflect it gently away from the shuttle in advance of the approach of its beak.

References Cited in the le of this patent UNTTED STATES PATENTS 1,469,066 Bell et al Sept. 25, 1923 1,885,927 Leveque NOV. 1, 1932 1,911,507 Hitchcock May 30, 1933 1,914,936 Ashworth June 20, 1933 2,051,085 IlSeman Aug. 18, 1936 2,390,908 Young Dec. 11, 1945 2,780,188 Schaefer et al Feb. 5, 1957 FOREIGN PATENTS 171,925 Austria July 25, 1952 

